Buffered trowel guard clearance system

ABSTRACT

A buffered guard clearance system for riding and manually pushed powered trowels adapted to allow finishing of a slab surface immediately adjacent an obstacle. The system comprises a movable wing displaceably coupled to the trowel guard cage and a buffer system mounted thereto. The wing is displaceable between a deployed position generally aligned with a lower ring of the cage and a retracted position. When retracted, an unguarded segment of the trowel rotor sweep is established that allows the finishing blades to be deployed immediately adjacent a wall or other obstacle. A displaceable coupling for moving the wing between the deployed position and the retracted position extends from the cage to the wing. The coupling comprises a sliding crossmember mounted on two spaced-apart brackets fixed to the cage. The crossmember supports the wing. The coupling may alternatively comprise electromechanical elements for displacing the wing between deployed and retracted positions. The buffer system contacts the wall to facilitate forward and rearward sliding movement of the trowel along the wall while finishing the slab immediately adjacent the wall. The preferred buffer system comprises a molding that snap-fits over the wing. The molding may be removed and replaced as necessary.

CROSS-REFERENCED TO RELATED APPLICATION

This application is a continuation-in-part of a U.S. patent applicationfiled on Dec. 21, 1993, Ser. No. 08/170,512, entitled Concrete RidingTrowel Guard Clearance System, and issued as U.S. Pat. No. 5,480,257, onJan. 2, 1996.

BACKGROUND

I. Field of the Invention

The present invention relates generally to motorized concrete finishingmachines. More particularly, the present invention relates to a guardclearance system for motorized trowels that will maintain the trowel ina spaced apart relationship with a wall (or other obstacle) whileallowing finishing of a slab surface immediately adjacent the wall.Known self-propelled trowels are classified in United States Class 404,Subclass 112.

II. Description of the Prior Art

As will be recognized by those skilled in the art, it is well known thatwet concrete must be appropriately finished. Motorized trowels are wellknown as machines for finishing wet concrete. Generally, motorizedtrowels come in two configurations, riding and manual walk-behindtrowels. Each type of trowel employs finishing blades that rest directlyon the concrete surface to be finished and that support the machine'sentire weight. A wide variety of manually pushed troweling machines havepreviously been proposed. However, self-propelled riding trowels arepreferred because they finish the concrete quicker and more efficiently.Motorized trowels generally employ pivoting blades. The trowel is passedover the concrete surface several times as the concrete sets. The pitchof the blades is adjusted for each pass.

Riding trowels generally include some form of frame from which two ormore rotors downwardly project. Each rotor has three or fourhorizontally oriented, symmetrically disposed blades. The rotors arepropelled by a self contained motor mounted on the frame that may belinked to rotor gear boxes. A yoke controlled bearing assembly is oftenemployed to vary blade pitch. The weight of the trowel and the operatoris transmitted frictionally to the concrete by the revolving blades. Theoperator sits on top of the frame and controls the movement of thetrowel through a steering system. Steering is accomplished by tiltingthe blade assemblies to generate differential vector forces. The forcespropel the frame across the concrete.

The present assignee, Allen Engineering, owns several prior motorizedtrowels and related improvements that may be considered relevant to thepresent invention. U.S. Pat. No. 4,577,993 issued on Mar. 25, 1986,discloses a power trowel with a cam actuated blade pitch adjustmentmechanism. Another patent issued to Allen is U.S. Pat. No. 5,108,220which is directed to a fast steering system for riding trowels. U.S.Des. Pat. No. D. 323,510 also discloses a riding trowel. The latter twopatents each disclose, in detail, a guard system typical of thoseemployed on riding trowels.

Riding trowels typical of those present in the art are disclosed in twopatents issued to Holz, U.S. Pat. Nos. 4,046,484 and 3,936,212. '212 isa three rotor riding trowel while '484 is a more popular two rotortrowel. Each of the rotors in the Holz patents has three radially spacedapart blades. The blades are guarded by stationary outer rings andinwardly projecting frame members. In the '212 reference, inner ringsare also employed to guard the blades.

Guard cages such as those disclosed in the above referenced patents arenecessary to protect workers from the rotating blades and to protect theblades from striking rigid structures which could damage the blades. Forexample, it is more desirable for the cage to strike an obstruction,such as a column, than the blades. This prevents damage to the bladesand the motor of the trowel. However, the use of such a guard cage makesfinishing surfaces near obstructions and walls difficult.

Maass, U.S. Pat. No. 4,027,991, assigned to M-B-W, Inc., discloses amanually pushed power trowel with a rigid, relieved guard ring section.This section when retracted can slide along a wall during finishingoperations to prevent contact between the blades and the wall. However,such a rigid section may "hang up" on a minor wall protrusions orimperfection. The rigid, retracted section could also easily damage thewalls by scarring or discoloring it.

In the past, riding trowels failed to provide sufficient control tofinish tight areas, such as a slab near the base of a wall. Therefore,it was unnecessary to provide a method for using riding trowelsimmediately adjacent walls or other structures. The advent of moreeasily controllable riding trowels, such as the trowel disclosed inaforementioned U.S. Pat. No. 5,108,220, renders the finishing of tightareas using a riding trowel more practical.

Hence, it is desirous to provide an improved guard clearance system formotorized riding trowels. Such a system would provide a portion oftrowel guard that would move to a retracted position, exposing a segmentof the finishing blade sweep. This exposed segment would then bemaneuvered into close proximity with an obstacle, such as a column, curbor wall, to finish the concrete adjacent the obstacle. The displaceablecoupling between the retractable portion of the guard and the trowel iseither manually or electromechanically manipulated. The guard clearancesystem should also employ a buffer system to allow the trowel to contacta wall and move along the wall. Such a buffer system would facilitatefinishing adjacent to the wall while still protecting the blades bypreventing contact with the wall. An ideal buffer system would also workwith a manually pushed power trowel.

SUMMARY OF THE INVENTION

My buffered guard clearance system for trowels protects the trowelblades while permitting the trowel to finish concrete surfacesimmediately adjacent obstacles such as walls, beams, etc. The system maybe used with either motorized riding trowels or manually pushed powertrowels. A unique buffer permits the trowel to slide along the wallduring finishing operations while maintaining adequate spacing betweenthe blades and the wall.

The system uses a movable section or wing attached to the fixed guardcage of a trowel by a displaceable coupling. The coupling permits thewing to move between a deployed position and a retracted position.

When deployed, the wing is disposed on the end of the trowel at the baseof the guard cage. In this position, the wing is aligned with thelowermost ring of the guard cage where it cooperatively protects thetrowel blades.

When the wing is retracted, an unguarded segment of the blade's sweep isexposed. This unguarded segment may be deployed immediately adjacent anobstacle to facilitate finishing. Thus the operator can maneuver thetrowel to position the unguarded segment near obstacles such as columns,curbs and walls.

The buffer maintains a preselected trowel-to-wall spacing duringfinishing. In the parent application, the buffer comprised a set ofrotating wheels. The novel buffer disclosed herein comprises areplaceable molding. The molding fits around the retractable wing toprotect the wall or other obstacle as trowel slides along it. Themolding allows the trowel to slip along the wall while finishing thesurface immediately adjacent the wall without harming it. The moldingand the retracted wing maintain selected trowel spacing from the wall,thereby avoiding contact between either the trowel or the blades and thewall. The molding preferably snap-fits onto the wing so that it can beeasily removed for replacement.

In one preferred embodiment, the displaceable coupling operatesmanually. However, the coupling may alternatively be a powered,electromechanical system remotely actuated by the operator. A manual andthree different types of powered systems are disclosed in the parentpatent. The different motive sources for the coupling are discussed indetail therein. Since the guard clearance system disclosed herein fitsboth the manual and the powered embodiments of the parent similarly,only the manual embodiment will be discussed in detail.

The manual coupling comprises an elongated, sliding crossmember thatextends between two spaced-apart brackets. The brackets mount to theframe beneath a reinforcing header. Studs protrude upwardly from eachbracket to pass through follower slots defined in the crossmember.Rotatable knobs may be tightened on the stubs to maintain selectedcrossmember placement. Adjustment of the wing is made by loosening thebolts and sliding the crossmember upwardly or downwardly along theslots.

The trowel must be stopped to retract or deploy the wing in the manualembodiment. The knobs are loosened and the wing then slides upwardlywith the loosened bolts guiding the follower slots. The bolts aretightened to hold the wing in the retracted position. The trowel is thenrestarted and the concrete adjacent the obstacle is finished. If theobstacle permits, the buffer molding is utilized to allow the trowel toslide along the obstacle without the blades contacting the obstacle. Toredeploy the wing, the trowel is stopped and the bolts are loosened. Thewing then slides downwardly to align with the cage bottom and the knobsare tightened.

In the electromechanical embodiments, the trowel does not need to bestopped to adjust the wing and buffering system. Instead, they areadjusted as necessary though remote operator controlled switches.Therefore, the use of electromechanical devices to retract the wing andcorrespondingly adjust the buffer system would result in significantsavings in both time and labor costs.

Thus, a fundamental object of the present invention is to provide aguard clearance system for powered trowels to facilitate concretefinishing immediately adjacent obstacles.

Another object of the present invention is to provide a clearance systemthat will maintain a powered trowel in a spaced apart relationship witha wall while finishing a slab.

A more specific object is to provide a clearance system for a multiplerotor riding trowels.

A related specific object is to provide a clearance system for amanually pushed power trowel.

Another object is to simplify concrete finishing operations by reducingrequired hand finishing.

A basic object is to provide an economical manual system in conformancewith the present disclosure.

A further object is to provide a clearance system for both riding andpower trowels of the character described that provides maximum safetywhile allowing finishing immediately adjacent obstacles.

A related object of the present invention is to provide a buffer systemto prevent inadvertent contact between the blades of a trowel and awall.

A related object of the present invention is to provide a buffer systemwith easily replaceable components.

Another basic object is to provide a greater degree of consistency in afinished slab surface by allowing a riding trowel to finish a greaterportion of the concrete surface.

These and other objects and advantages of the present invention, alongwith features of novelty appurtenant thereto, will appear or becomeapparent in the course of the following descriptive sections.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following drawings, which form a part of the specification andwhich are to be construed in conjunction therewith, and in which likereference numerals have been employed throughout wherever possible toindicate like parts in the various views:

FIG. 1 is a front isometric view of a riding trowel mounting a manualembodiment of my guard clearance system, with the wing deployed;

FIG. 2 is a front isometric view of a manual push power trowel mountingmy guard clearance system with the wing deployed;

FIG. 3 is an enlarged, partially fragmented front isometric,environmental view of the riding trowel shown in FIG. 1, with portionsomitted or broken away for clarity;

FIG. 4 is a cross-sectional view taken along line 4--4 of FIG. 3,showing the retractable wing and buffer molding;

FIG. 5 is a cross-sectional view similar to FIG. 4, but showing thebuffer molding in a moved position;

FIG. 6 is a fragmented, environmental front elevational view with thewing deployed;

FIG. 7 is a fragmented, environmental front elevational view with thewing retracted and the buffer molding contacting a wall;

FIG. 8 is a fragmented, environmental top plan view with the wingdeployed; and,

FIG. 9 is a fragmented, environmental top plan view with the wingretracted and the buffer molding contacting a wall.

DETAILED DESCRIPTION

Turning now to the drawings, the manual embodiment of my riding trowelguard clearance system is broadly designated by the reference numeral 20in FIGS. 1 through 9. The guard clearance system is adapted to be usedwith either a riding trowel or a manual push trowel. Both types ofpowered trowels 25 (i.e., riding trowel 26 (FIG. 1) and manual pushtrowel 26A (FIG. 2)) have several common characteristics. Generally,each trowel 25 has a front 27 defined as the direction of travel 28faced by an operator, an opposite rear 29 and spaced apart ends or sides30.

However, there are some differences. For example, riding trowels 26normally employ two or more rotors 35 that each have radially spacedapart concrete finishing blades 37. On the other hand, manual pushtrowels 26A generally employ only one rotor 35A with correspondingblades 37A. In both cases, the rotors 35, 35A are rotated at high speedto finish concrete, and the blade pitch may be varied depending on thecured condition of the concrete and the desired finish.

Both types of trowels 25 employ a guard cage 40 to prevent inadvertentcontact between the rotor or blades and workers or obstacles. The cage40 is generally secured to a frame 39 associated with the trowel 25. Thecage 40 is comprised of at least one lower ring 42. Additional spacedapart upper rings 43 may also be included as cage size increases. Spokes45 generally extend perpendicularly to the rings 42 and 43, providingrigidity to the cage. The guard cage 40 disposed about the riding trowel25 is generally round or oval shaped. For example, the front 27 and rear29 of the guard cage 40 of a riding trowel may be flat while the ends 30are curved while manual power trowels front 27 and rear 29 are round andthe ends 30 are flat.

Trowel structural details including frame construction, power traindesign, rotary blade suspension, motor control, steering linkages andthe like are disclosed in U.S. Pat. Nos. 4,577,993, 5,108,220, 4,046,484and 3,936,212. These patents are hereby incorporated by reference forpurposes of disclosure. Also, as previously stated, this application isa continuation-in-part of a U.S. patent application filed on Dec. 21,1993, Ser. No. 08/170,512, entitled Concrete Riding Trowel GuardClearance System, and issued as U.S. Pat. No. 5,480,257, on Jan. 2,1996, the teachings of which are again incorporated by reference.

Guard cages 40, such as those disclosed in the above referenced patents,are necessary to protect workers from the rotating blades 37, 37A. Thecage also prevents the blades from striking rigid structures that coulddamage the blades. Normally, it is more desirable for the cage 40 tostrike an obstruction, such as a column or wall, than the blades becausethe cage is usually easier and cheaper to repair. The cage thus preventsdamage to the blades and the trowel motor. However, the use of a guardcage 40 makes finishing surfaces near obstructions and walls difficult.

My clearance system 20 allows a trowel 25 to finish a slab surface 44immediately adjacent an obstacle such as a wall 46, column or curb. Whenused to finish a slab 44 adjacent a wall 46, the present clearancesystem 20 is adapted to maintain the trowel 25 in a spaced apartrelationship with the wall 46 while allowing finishing of the slab 44surface immediately adjacent the wall 46 (FIGS. 6 through 9). The system20 is comprised of a movable wing 50 of trowel guard cage ring 42coupled to the cage 40 or trowel frame 39 by a displaceable coupling 55.

Preferably, wing 50 comprises an elongated flat arc 52. Arc extends fromcage ring end 42A to cage ring end 42B. Arc 52 comprises three flatstrips 52A, 52B and 52C. The front strip 52A extends outwardly from thelongitudinal axis of cage ring end 42A at approximately twenty-fivedegrees. Central strip 52B joins 52A at an obtuse angle and it isparallel to the axis of travel 28 of trowel 25. Rear strip 52C joinscentral strip 52B oppositely to front strip 52A. Rear strip 52C extendsfrom central strip 52B to cage ring end 42B.

Wing 50 may be disposed in either a deployed position, adjacent lowerring 42 (FIGS. 1-3, 6 and 8) or in a retracted position (FIGS. 7 and 9).When deployed, wing 50 is aligned with the lower ring 42 and it extendsbetween ends 42A, 42B. When wing 50 is retracted, an unguarded segment57 of the rotor blades's sweep is exposed. This unguarded segment 57 maybe deployed immediately adjacent an obstacle to facilitate finishing(FIG. 7). During such finishing, band 52 slides along wall 46 to protectsegment 57. A buffering system 60 prevents band 52 from catching on thewall 46 and it also protects the wall 46 from chipping or discoloring.

In one preferred embodiment, buffer system 60 comprises a a hollow,elongated molding 61 (FIGS. 3-5). Buffer molding 61 mounts on wing 50.The molding 61 permits the trowel 25 to slide along the wall 46,insuring that the blades will not strike the wall 46 and be damaged.Preferably buffer molding 61 is molded from plastic or another similarmaterial. Molding 61 comprises three shells 62A, 62B and 62C that coverrespective arc strips 52A, 52B and 52C (FIGS. 3-5). preferably, molding61 has a closed top 63 and an open bottom 64. Opposing tabs 64A, 64Bprotrude outwardly from respective sides 65A, 65B along bottom 64.

Molding 61 may be easily installed or removed from arc 51 as desired.Molding 61 is installed by first placing it upon the top of arc 51.Bottom 64 is aligned with arc top 51A and then pushed downwardly in thedirection shown by arrow 66A (FIG. 5). When tabs 64A, 64B pass arcbottom 51B, they snap into a locking configuration (FIG. 4).

Removal of molding 61 from arc 51 proceeds similarly. First, tabs 64A,64B are spread away from bottom 51B. Then molding 61 is moved upwardlyin the direction shown by arrow 66B until it passes top 51A (FIG. 5).

The adjustability of the coupling 55 allows the use of the presentinvention with varying widths of finishing rotor elements. For example,it might be desirous to place the present invention on an adjustablewidth riding trowel 26, as illustrated in FIG. 1. This type of trowel 26may employ either concrete finishing blades 37 or concrete finishingpans fitted over blades 37. Alternatively, it might be desirous to placethe present invention on a manual push power trowel 26A, as illustratedin FIG. 2. This type of trowel 26A generally employs smaller concretefinishing blades 37A and correspondingly smaller concrete finishingpans. Therefore, it is necessary that the displaceable coupling 55 beadjustable to facilitate the proper spacing with the wall 46.

The displaceable coupling 55 may be either manual or electromechanical.The preferred manual coupling 55 is shown in FIGS. 1 through 9. However,as discussed previously, alternative, powered couplings may be easilyadapted to function with the invention disclosed herein.

The manual coupling 55 comprises a pair of spaced apart brackets 70. Anelongated, flat crossmember 72 extends between brackets 70 to formcoupling 55. Longitudinal, spaced-apart follower slots 75 are defined ineach end of crossmember 72 adjacent brackets 70 respectively. The slots75 are penetrated by threaded studs 76 protruding from brackets 70. Thewing 50 is held in place by two studs 76 passing through thelongitudinal slots 77. Each stud 76 extends outwardly from a respectivebracket 70.

The studs 76 are each capped by a rotatable knob 77 that facilitatesoperator adjustment. Wing 50 is displaced by loosening knobs 77 and thensliding the wing 50 upwardly and inwardly, with the slots 75 followingthe studs 76. When adjusted properly, wing 50 is secured by tighteningknobs 77 to maintain the wing in the retracted position (FIGS. 7 and 9).

Preferably, a reinforcing, cage header 78, having a generallyrectangular shape, spans spokes 45. Header 78 provides additionalstability for cage 40, allowing the use of a movable wing 50.Crossmember 72 also lends rigidity to both the wing 50 and couplingsystem 55.

Operation

In operation, system 20 is employed to finish concrete immediatelyadjacent an obstacle such as a wall 46, column, or curb. To finish theconcrete immediately adjacent a column or curb, the wing 50 is retractedand the trowel 25 is moved as close as possible to the obstacle and thenfinishing is completed. Whenever a wall 46 is the obstacle, the buffermolding 60 slides across the wall, allowing finishing as close aspossible to the wall 46 without damaging it or the finishing blades.

When the trowel 25 approaches a wall 46, wing 50 is retracted. In thepreferred manual embodiment 20, the trowel 25 must be stopped and theknobs 77 loosened. The wing 50 then slides upwardly along the slots 75in brackets 70 until a desired configuration is reached. Then, knobs 77are tightened to secure wing 50 in place. The trowel 25 is thenrestarted and driven along the wall 46. Contact between the molding 61and the wall 46 is maintained to properly finish the concrete along thebase of the wall 46. To redeploy the wing 50, the trowel 25 is stoppedand the knobs 77 are loosened. The wing 50 then slides downwardly untilit is adjacent cage ring 42. Then, knobs 77 are tightened to maintainwing 50 placement.

From the foregoing, it will be seen that this invention is one welladapted to obtain all the ends and objects herein set forth, togetherwith other advantages which are inherent to the structure.

It will be understood that certain features and subcombinations are ofutility and may be employed without reference to other features andsubcombinations. This is contemplated by and is within the scope of theclaims.

As many possible embodiments may be made of the invention withoutdeparting from the scope thereof, it is to be understood that all matterherein set forth or shown in the accompanying drawings is to beinterpreted as illustrative and not in a limiting sense.

What is claimed is:
 1. A self propelled motorized riding trowel forfinishing a concrete surface, said trowel comprising:downwardlyprojecting rotary blade means for contacting and finishing concrete;cage means surrounding said trowel for guarding said blade means, saidcage means comprising: arc means selectively displaceable between adeployed position mated to said cage means for guarding said blade meansand a retracted position exposing at least a portion of said blademeans; coupling means comprising spaced-apart brackets and an elongatedcrossmember extending therebetween that cooperatively support said arcmeans for displacing said arc means between said deployed position andsaid retracted position, thereby establishing an unguarded cage segmentallowing said finishing blades to be deployed immediately adjacent awall; and, buffer means secured to said arc means between said bracketsfor contacting said wall and allowing movement of said trowel along saidwall while finishing the surface immediately adjacent said wall, saidbuffer means comprising an easily replaceable resilient molding, saidmolding comprising a shell with a buffering exterior adapted tonon-destructively slide over said wall, said shell having a pair ofspaced-apart tabs that snap-fit onto the bottom of said arc means totemporarily couple said resilient molding to said arc means;whereby saidcage means maintains said trowel in a spaced apart relationship withsaid wall while the trowel finishes the concrete surface immediatelyproximate said wall.